Defibrillator with training features and pause actuator

ABSTRACT

A defibrillator featuring a treatment mode and a training mode comprises an energy source, an electrode connector, a controller, and training mode circuitry. The controller comprises a feature for connecting the energy source to the electrode connector and a pause actuator for permitting a user to inhibit electrical stimulation when no longer required. The training mode circuitry simulates the operation of the defibrillator in treatment mode. The defibrillator also includes a method of operating comprising the steps of: 1) providing a defibrillator having an energy source, a controller, and electrode connectors, wherein the controller further comprises circuits for actuating the defibrillator to deliver a defibrillation shock from the defibrillation energy source to the electrode connectors and 2) operating the defibrillator in a training mode to simulate delivery of a defibrillation shock from the energy source to the electrode connectors without delivering a defibrillation shock from the energy source to the electrode connectors.

This application is a CONTINUATION of application Ser. No. 08/351,897filed 08 Dec. 1994, now U.S. Pat. No. 5,611,815 issued Mar. 18, 1997.

BACKGROUND OF THE INVENTION

This invention relates to defibrillators, particularly semi-automaticand automatic external defibrillators, having built-in trainingfeatures. The invention also relates to defibrillator features thatfacilitate training and use of the defibrillator.

One frequent consequence of heart attacks is the development of cardiacarrest associated with a heart arrhythmia, such as ventricularfibrillation. Ventricular fibrillation may be treated by applying anelectric shock to the patient's heart through the use of adefibrillator. The chances of surviving a heart attack decrease withtime after the attack. Quick response to a heart attack by administeringa defibrillating shock as soon as possible after the onset ofventricular fibrillation is therefore often critically important.

Training potential defibrillator operators on the proper use of adefibrillator can reduce defibrillator deployment time. The prior arthas therefore developed two different approaches to defibrillatoroperator training. In the first approach, the trainee actually operatesthe defibrillator as if delivering an electrical shock to treat apatient instead of delivering the shock to a live patient, however, thedefibrillator delivers the shock to a patient simulator, such as amannequin or an electronic device. See, e.g., Ungs et al. U.S. Pat. No.5,275,572.

In the second approach, the trainee does not use an actual defibrillatorat all. Instead, training is conducted on a separate training devicewhich looks like a defibrillator and simulates the operation of adefibrillator. The training device cannot actually be used to deliver adefibrillation shock to a patient, however. Medical organizationsfollowing this defibrillator training approach must therefore have twosets of instruments, one for training and one for actual use.

SUMMARY OF THE INVENTION

Prior art defibrillators and defibrillator training techniques weredirected to emergency medical personnel who use defibrillatorsrelatively frequently and can therefore maintain their defibrillator useskills. As the use of defibrillators by police, firefighters and othernon-medical personnel becomes more common (i.e., as the ratio ofdefibrillators to patients increases), the use frequency of eachdefibrillator by each potential defibrillator operator decreases. Thedefibrillator must therefore be easy to use, and defibrillator operationmust be easy to train. Moreover, since more people will need to betrained, training costs per person must be kept at a minimum.

This invention is a defibrillator with built-in training features. In apreferred embodiment, the invention is a defibrillator having atreatment mode and a training mode, comprising an energy source; anelectrode connector; a controller, the controller comprising means forconnecting the energy source to the electrode connector; and trainingmode means for simulating the operation of the defibrillator intreatment mode.

The invention also includes a method of operating a defibrillatorcomprising steps of providing a defibrillator comprising adefibrillation energy source, a controller and electrode connectors, thecontroller comprising means for actuating the defibrillator to deliver adefibrillation shock from the defibrillation energy source to theelectrode connectors and operating the defibrillator in a training modeto simulate delivery of a defibrillation shock from the energy source tothe electrode connectors without delivering a defibrillation shock fromthe energy source to the electrode connectors.

The invention will be described in more detail below with reference tothe drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of a defibrillator for use with thisinvention.

FIG. 2 is a schematic block diagram of a defibrillator implementing thisinvention.

FIG. 3 is an exploded view of the defibrillator shown schematically inFIG. 2.

FIG. 4 is a perspective view of the defibrillator shown schematically inFIG. 2 and shown in an exploded view in FIG. 3.

FIG. 5 is a detail of an icon used in connection with the defibrillatorshown in FIGS. 3 and 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Defibrillators fall into three general categories. Manual defibrillatorscharge and deliver shocks to patients solely in response to useractuation or a user request. Automatic defibrillators charge and delivershocks to patients solely in response to ECG data collected from thepatient and analyzed by the defibrillator. Semiautomatic defibrillatorsanalyze patient ECG data and recommend shocks (or recommend that noshock be delivered) but require user actuation to deliver the shock tothe patient. This invention may be implemented in all three kinds ofdefibrillators.

FIG. 1 is a schematic representation of a defibrillator, which may bemanual, semi-automatic or automatic. Defibrillator 10 has an energysource 12, electrode connectors 14, and switches 16 between the energysource and the electrode connectors. Energy source 12 may be made up ofan energy storage medium 22 (e.g., a battery), a capacitor or capacitorbank 24, and a charging circuit 26.

A controller 18 (such as a microprocessor) within defibrillator 10controls the operation of energy source 12 and switches 16 to deliver anelectrical pulse to electrode connectors 14. Controller 18 receivesinput through a user input 20, which may be, e.g., one or more buttonsor other actuators, one or more digital or analog ports, or combinationsthereof. Controller 18 also sends out information through output 28which may include a display, digital or analog ports, or combinationsthereof. If the defibrillator is automatic or semiautomatic, controller18 includes an ECG signal analyzer. Defibrillator 10 also has a memory30 for storing digital and/or analog information.

Defibrillator 10 may be used to deliver an electrical pulse or shock toa patient. For example, if defibrillator 10 is a semi-automaticdefibrillator, it may be used as follows. First, the user attacheselectrodes at one end to electrode connectors 14 and at their other endto a patient. The ECG analyzer of the defibrillator controller 18 thenanalyzes ECG signals obtained through the electrodes to determinewhether it is advisable to deliver a shock to the patient. Thedefibrillator displays its shock/no shock advice on output 28. If ashock is advised and the user decides to deliver a shock, then the usermay actuate the controller through user input 20 to deliver the shock.

The user's decision of whether or not to actuate the defibrillator todeliver a shock to the patient may depend on more than thedefibrillator's shock/no shock recommendation. For example, if thepatient is conscious, then the user will likely ignore a shockrecommendation. Also, the defibrillator may provide more detailedinformation than the simple shock/no shock recommendation, such asinformation on the quality of the electrical connection between theelectrodes and the patient. The defibrillator may also display theactual ECG waveforms. This information and other information from thedefibrillator, the patient or the surrounding circumstances can affecthow the user should operate the defibrillator to provide the mosteffective care for the patient. Defibrillator users should therefore betrained on the operation of the defibrillator and on the best responsesto different patient treatment scenarios.

The defibrillator of this invention may be operated in at least twodifferent modes. The first is the patient treatment mode, describedabove. The second mode is a training mode in which the defibrillatoroperates as if there were a patient present and requiring treatment. Inthe training mode, however, there is no patient providing ECG signals,and the defibrillator does not deliver any electrical pulse from theenergy source to the electrode connectors.

The defibrillator 10 shown schematically in FIG. 1 may be switched froma patient treatment mode to a training mode through the use ofdefibrillator operation mode control 32. When switched to training mode,controller 18 simulates the operation of the defibrillator for treatinga patient by simulating the collection of patient ECG data (e.g., byretrieving a stored patient ECG waveform from memory 30) and simulatingthe delivery of an electrical pulse to the patient in response toactuation by the trainee.

When switched to training mode, controller 18 also preferably disablesenergy source 12 so that capacitor 24 cannot charge. The disabling maybe positive (by actually removing the capacitor charger and/or deliveryswitch from operation) or negative (e.g., by omitting the softwarecommands necessary to operate the capacitor charger and/or deliveryswitch). This feature minimizes the likelihood that the defibrillatorwill accidentally deliver a shock when in training mode.

The details of a defibrillator training mode implemented according tothis invention depend in part on the defibrillator design and in part onlocal defibrillator user protocols. The following description describesthe use of the invention for one particular defibrillator design and forone particular user protocol. It should be understood, however, that theinvention is not limited to this defibrillator design or to this userprotocol.

A suitable defibrillator for use with this invention is disclosed inU.S. patent appl. Ser. No. 08/227,553, "Electrotherapy Method andApparatus," filed Apr. 14, 1994, and U.S. patent appl. Ser. No.08/240,272, "Defibrillator With Self-Test Features," filed May 10, 1994.The disclosures of these two patent applications are incorporated hereinby reference. The following example illustrates the use of thisinvention with the defibrillator described in these two patentapplications.

FIG. 2 is a block diagram showing a preferred configuration for thedefibrillator of this invention. As shown in FIG. 2, defibrillator 130has a power source such as a removable battery 132, a controller such asCPU 134, and a high voltage delivery system 136 including a capacitor orcapacitor bank and appropriate switches (not shown) to deliver a pulseof electrical energy to an electrode connector or interface 138 and thento a patient via electrodes 140. Delivery of the electrical pulse iscontrolled by CPU 134. A test and isolation relay 176 and a test load178 are also provided.

An ECG front end system 135 acquires and preprocesses the patient's ECGsignals through electrodes 140 and sends the signals to CPU 134 via asystem gate array 156. System gate array 156 is a custom applicationspecific integrated circuit (ASIC) that integrates many of thedefibrillator's functions, such as display control and many of theinstrument control functions, thereby minimizing the number of parts andfreeing up main CPU time for use in other tasks. The system gate arraycould be replaced by discrete logic and/or another CPU, of course, asknown in the art.

The defibrillator shown in FIG. 2 also has a memory device 180 (e.g., aremovable PCMCIA card), a microphone 181, a speaker 182, a LCD panel 183and illuminated push-button controls 184.

A system monitor 142 mediates the defibrillator's self-testing functionsby watching for scheduled test times and unscheduled power-on events.The system monitor generates test signals periodically at scheduledtimes and in response to specified events. The system monitor is alsoresponsible for operating a fail-safe defibrillator status indicator ordisplay 158. The system monitor communicates test signals to the CPU viaa communication channel, and the CPU controls and gathers informationfrom tested defibrillator components via other communication channels,some of which pass through system gate array 156.

FIGS. 3 and 4 show an implementation of the defibrillator shownschematically in FIG. 2. The defibrillator includes a molded two-partplastic housing with an upper case 280 and a lower case 281. A mainprinted circuit board ("PCB") 286 supports a capacitor 232 (part of thehigh voltage delivery system 136 of FIG. 2), an electrode connector 282(electrode interface 138 of FIG. 2), a PCMCIA memory card 283(corresponding to memory device 186 of FIG. 2) and a PCMCIA memory cardejector mechanism 284. The PCMCIA memory card 283 lies within a PCMCIAmemory card slot 295 on PCB 286.

A keyboard PCB 285 and a display PCB 287 are disposed between the mainPCB 286 and the upper case 280. Keyboard PCB 285 interfaces with thedefibrillator's operator buttons 297 and 298 (the illuminatedpush-button control 184 of FIG. 2), and display PCB 287 operates thedefibrillator's LCD display 288 (element 183 of FIG. 2). A displaywindow 289 in the upper case permits display 288 to be seen by anoperator.

A battery assembly 299 (corresponding to battery 132 of FIG. 2)consisting of a battery housing 292 and six lithium-manganese dioxideprimary cells 294 is disposed in upper case 280 so that the batteriesare in electrical contact with the capacitor charge circuits and othercircuits of main PCB 286. The battery assembly has a latching mechanism296 for attaching and detaching the battery assembly to and from thedefibrillator.

The location of the battery assembly in front of the PCMCIA memory cardslot prevents the defibrillator operator or others from accessing thePCMCIA card while the defibrillator is powered up and operating. Thisarrangement protects the operator and patient from accidental shocks andprotects the defibrillator itself from damage caused by inadvertentremoval of the PCMCIA card during operation.

The defibrillator shown in FIGS. 2-4 has features that make it easier totrain users in training mode and therefore easier to use in patienttreatment mode. These features will be explained in the context ofoperating the defibrillator in a semi-automatic operating mode to treata patient.

Semi-automatic mode may be entered by depressing on/off button 298.After any power-on self-tests (e.g., as described in Ser. No.08/240,272), the defibrillator displays its operational status ondisplay 288. If the defibrillator is operational, it begins charging itscapacitor and proceeds to electrode analysis.

If the defibrillator determines that electrodes have not yet beenattached to electrode connector 282, display 288 tells the user (such aswith an "Attach Pads" message) and a light 300 adjacent the connectorbegins flashing to show the user where the electrodes connect to thedefibrillator. In addition, the electrode connector is marked withconnection icon 301, as shown in FIG. 5, to help guide the user to theelectrode connector and to show the user how to place the electrodes onthe patient. If the electrodes are attached but are not operational forsome reason (as determined by any electrode attachment test known in theart), the defibrillator displays a message such as "Replace Pads" ondisplay 288. The "Attach Pads" and "Replace Pads" or other visualmessages may be accompanied by voice prompts from the defibrillator.

Once the electrodes have been attached and have been determined by thedefibrillator to be operational (in a manner outside the scope of thepresent invention), the defibrillator begins analyzing the patient's ECGto make "shock" or "no shock" decisions in a manner known in the art. Inthis state, the defibrillator displays an "Analyzing" or similar messageon display 288. The defibrillator may also analyze the quality of theECG information it is receiving and will display a message such as"Analyzing Stopped" (possibly accompanied by a voice prompt) if asuspected motion artifact (or other artifact) appears in the ECG signal.

If the defibrillator makes three consecutive "no shock" decisionsaccording to its analysis protocol, the defibrillator displays "No ShockAdvised" or a similar message on display 288 and continues monitoring.If, however, the defibrillator makes a "shock" decision, it immediatelycompletes charging its capacitor and displays a message such as "PrepareTo Shock." These visual messages may be accompanied by voice prompts. Inaddition, the defibrillator preferably emits a tone during capacitorcharging, with the pitch of the tone rising as the charging nearscompletion.

The defibrillator becomes armed when the capacitor is fully charged. Thedefibrillator indicates this condition with illuminated shock button 297and both visual and voice prompting: first, "Prepare To Shock--StandClear", then "Shock Advised--Press To Shock" or similar messages. Inaddition, a continuous tone alternates with the voice prompts. The userdelivers a shock to the patient by depressing shock button 297. Afterdelivery of a shock, the defibrillator emits a "Shock Delivered" (or itsequivalent) visual and/or voice prompt, then transitions to an analysisstate.

The user may disarm the device by depressing on/off button 298.

After delivering a number shocks (with the number being programmable),the defibrillator of this embodiment pauses to permit CPR to beperformed on the patient. The length of the pause is programmable by theuser. During the pause, the defibrillator display 288 shows the message"Attend Patient" and the time remaining in the pause.

In addition to the CPR pause, the defibrillator may have a pause button(such as one of the buttons 184 in FIG. 2) that places the defibrillatorin a pause state for a period of time. In the pause state: all audibleprompts are disabled; if the defibrillator had been charging, it stopscharging; if the defibrillator had been armed, it disarms; and thedefibrillator returns to a precharged state. The pause state ends whenthe pause button is hit again or at the end of the pause period. Thelength of the pause period may be programmable.

The defibrillator display 288 may show real time patient ECG waveforms,heartrate, number of shocks delivered, elapsed time, defibrillatorcondition (e.g., low battery warning) and any other relevantinformation. The defibrillator may also be able to display data fromearlier uses in an Event Review mode.

Similar defibrillator operations may be provided for automatic andmanual operation of the defibrillator.

According to this invention, the defibrillator's training mode simulatesthe defibrillator's operation modes. To enter training mode, the userremoves battery assembly 299, inserts a PCMCIA training card in PCMCIAslot 295, and replaces the battery assembly. This act activates theinitial training sequence. In training mode, software on the PCMCIA cardcontrols operation of the defibrillator; the code controlling treatmentmode becomes unavailable. The training software does not operate thecapacitor charging circuit and or the high voltage delivery circuit, sothat the defibrillator's ability to deliver a shock is effectivelydisabled.

In addition, the defibrillator displays a "Training Mode" messagecontinually while in training mode. Thus, because the training code ison the training card, and because the training card advertises itspresence within the defibrillator, there is very little chance a userwould attempt to treat a patient with the defibrillator while it is intraining mode. If the defibrillator's battery is dead or absent and theuser inserts a new battery while the training card is inserted, thedefibrillator will power up and display its "Training Mode" message andwill tell the user that the training card must be removed in order toleave training mode.

The preferred embodiment offers a choice among multiple trainingscripts, each made up of sequences of ECG rhythms, such as ventricularfibrillation, fine ventricular fibrillation, ventricular tachycardia,normal sinus, normal sinus to ventricular fibrillation transition, andasystole. The desired script may be chosen by the trainee or by aninstructor before the defibrillator is turned over to the trainee. Thetrainee begins the script by pressing the on/off button 298, and thedefibrillator guides the trainee through the script using the audibleand visual prompts the defibrillator would use in when actually treatinga patient, such as those described above. The training script would mostlikely include a shock recommendation from the defibrillator followed byactuation of the shock delivery button by the trainee. The trainee mayexit training mode by removing the battery and PCMCIA training card fromthe defibrillator.

The script may be placed on the training cards by a certification ortraining authority. Alternatively, a trainer or other user may designpersonalized training scripts of portions of training scripts.

The training mode of this invention may be performed with or withoutattaching the defibrillator electrodes to the defibrillator or to aconductive surface, as determined by the selected script. For example,the trainee could select a script option in which attachment of theelectrodes is assumed.

In the preferred embodiment, the defibrillator provides training onmaintenance functions as well as treatment functions. For example, oneor more of the training scripts provide instruction on steps to followwhen the defibrillator displays a low battery warning or if thedefibrillator indicates that some other self-test has failed.

The training card may be provided With a memory for recording thetrainee's actions in response to the training script, such as the waythe trainee operated the defibrillator's controls. This information maybe used to evaluate the trainee's performance, for example by comparingthe trainee's operation of the defibrillator with preset operationstandards. Alternatively, the memory used for this training evaluationfunction may be located within the defibrillator itself and not part ofthe training card.

Certain defibrillator use protocols require users to fill out "runreports" detailing the condition of the patient and the treatmentapplied using the defibrillator. The operator training course couldinclude the use of run reports filled out after a training session. Ifthe training card has memory to record the training session as discussedabove, the training card and run report may be submitted for evaluationby a certification authority. In fact, training could be initiated andevaluated from a remote location by mailing a training card to a traineeand receiving back the results (e.g., training card and run report) ofthe training session.

The preferred embodiment above was discussed primarily in connectionwith a particular semi-automatic defibrillator configured to operateaccording to a particular protocol. Other defibrillators, otherprotocols and other defibrillator training scenarios may be used, ofcourse, without departing from the scope of this invention.

For example, in the preferred embodiment, the device shows that it is intraining mode by displaying an appropriate message. This feature isimportant to prevent a user from attempting to treat a patient while thedevice is in training mode. Other ways of identifying training mode arepossible, of course, such as a ribbon or marker extending from thetraining card; a mechanical flag that displays only during trainingmode; or a light or other electronic indicator that displays only duringtraining mode.

In another alternative embodiment, the defibrillator could be switchedto training mode by inserting a special training battery instead of byinserting a training card. Also, training mode could be initiated by aswitch or other control on the defibrillator.

In the preferred embodiment, all training code is on the training card.In alternative embodiments, the training code could be contained withinthe defibrillator itself.

We claim:
 1. A method for a user to operate an automatic orsemiautomatic external defibrillator to treat a patient, the methodcomprising the following steps:providing an automatic or semiautomaticexternal defibrillator to the user; activating the defibrillator toprovide therapy to the patient; placing the defibrillator in a pausestate by the user actuating a pause actuator; ending the pause state. 2.The method of claim 1 wherein the placing step comprises disablingdefibrillator audible prompts.
 3. The method of claim 1 wherein theactivating step comprises charging an energy source and the placing stepcomprises ceasing charging of the energy source.
 4. The method of claim1 wherein the activating step comprises arming the defibrillator and theplacing step comprises disarming the defibrillator.
 5. The method ofclaim 1 wherein the ending step comprises the user actuating adefibrillator actuator.
 6. The method of claim 1 wherein the placingstep comprises the user actuating a button on the defibrillator.
 7. Themethod of claim 6 wherein the ending step comprises the user actuatingthe button.
 8. The method of claim 1 wherein the ending step comprisesending the pause state after a predetermined pause period.
 9. The methodof claim 8 further comprising programming the predetermined pauseperiod's length.